Vauxhall Corsa pulling off problems

every time i pull off the engine seems to lose the power and the revs die right down so i have to dip the clutch and give it a load of revs to pull away. also when im driving at a steady speed and feathering the throttle, it feels like its kicking, just like when i pull off from junctions or trafic lights. i just replaced my crank sensor and air flow meter for other issues, is this another problem?? the fuel filter was replaced last year and the spark plugs are ok so maybe a vacum leak somewhere??? please help.!!!